The invention relates to a device in the form of a combined non-return valve and rat killer for internal fitting in a piping system such as a sewer pipe, where the device comprises a swinging valve, which in a passive position is open for continuous flow through the pipe and in active position is in a down-swung position, where the valve blocks back-flow.
Along with increased volumes of rainwater, which are characterized by large amounts over a short period of time, the problem of overloaded sewer pipes and resulting damages and nuisance to buildings and surrounding grounds, such as roads and the like, is increasing.
For drainage of this so-called flood and/or back-flow, valve-like devices are known which include, for example, spherical floating bodies, which in the event of rising water will move upwards toward a valve seat in the drain. Most commonly used is a non-return flap where the flap follows the flow of water. All parts are in direct contact with sewage and therefore exposed to deposits which will eventually lead to problems such as lower flow and problems with leakage. This is being remedied with annual inspections and possible cleaning, and will after a few years be inoperative, because the amount of dirt deposited on the flap will cause the flap to malfunction and leak.
Over the years attempts have been made to limit the number of sewer rats using electrical or mechanical traps and poison but so far without satisfactory results, either because the water flow through the pipe or the sewer pipe is reduced or due to inaccuracy when serving as a rat killer.